Conventionally, a certificate verification server which accepts an inspection request from a client and verifies a certificate has been proposed (refer to Hitachi, Ltd., “Certificate verification server>Product introduction” http://www.hitachi.co.jp/Prod/comp/app/kensho/product.html, acquired Sep. 24, 2015).
In addition, an analysis device is proposed which, when a terminal performs any of known illegal communications, acquires access URLs of communication destinations used by the terminal for communication within a time slot of a predetermined range from a start time of the illegal communication and, based on a frequency at which the access URL of each acquired communication destination appears in the illegal communication and other illegal communications, detects the access URL of a communication destination related to the illegal communication among the access URLs of the respective communication destinations (refer to Japanese Patent Application Publication No. 2015-082769).